Plot

Act I: "Wait, the Butterfly Derby is when? And what?"

While on a double date, accompanied by Fry and Kif, Amy and Leela make various catty comments to each other which they insist are a sign of their true friendship. They continue this behaviour during a delivery of moon rocks which are being returned to their place of origin. After the delivery, the Hydroponic Farmer invites the crew to a Butterfly Derby as an example of moon culture. The sport involves pairs of women in skimpy costumes fighting each other while they fly with wings strapped to their arms. Leela and Amy volunteer to fight the reigning champion Murderflies and are badly beaten, but show enough promise that they are offered a position as a regular team.

Naming themselves the Wingnuts, Leela and Amy continue to lose every match, until they learn about a nutritional supplement called Nectar which will help to bulk up their flying muscles.

Act II: "It's not easy being a Derby wife."

Taking Nectar regularly improves their performance drastically, but puts a strain on their relationships as they become abusive and neglectful to Fry and Kif. Leela and Amy run into trouble when they qualify for a championship match against the Murderflies, who have bought up the entire available supply of Nectar, leaving Leela and Amy in desperate straits. The Professor reveals that Nectar comes from a flower native to Kif's planet, Fry suggests that the four of them (with Bender) make a trip there to find it; he hopes that having some time alone will give them an opportunity to rekindle their romances.

At the Butterfly Sanctuary where the Nectar can be found, the Grand Midwife warns them that it is mating season, and that something terrible will happen to them if they provoke the anger of the male butterfly. As the girls are off finding Nectar, the men accidentally find a male butterfly, and it sprays Fry with a horrible smelling liquid. They meet up again to spend the night with Kif's parents, who strictly order them to sleep in different bedrooms. However, Leela and Amy both find Fry's new scent irresistible and both sneak into his bed that night.

Act III: "Let's get this party ended."

The Professor explains that the women's uncontrollable lust is caused by the fact that Fry has been sprayed by male butterfly pheromones, and the Nectar has made Leela and Amy respond to them as female butterflies would, much to Kif's jealousy and anger. They decide that they must quit Nectar completely. Although they find the detox difficult and suffer withdrawal symptoms, Leela and Amy manage to overcome their dependency just in time for their championship match. Meanwhile, the pheromones have made Fry feel sick, and he has built a cocoon for himself on the ship.

At the fight, Leela and Amy are no match for the Murderflies. As they are about to be thrown into a pit of lava, Fry enters the building; he has transformed into a butterfly, and the Murderflies are so attracted to him that they forget the match entirely. Although things do not look good for Fry, he ultimately sheds the butterfly anatomy and returns to his normal self.

It has so far released eight items: A design of a new character, Tank, which revealed the episode's plot on 30 May,[3] a promotional picture showing Amy and Leela as wingnuts on 31 May,[4] part of the storyboard showing Leela kiss Fry on 1 June,[5] a design of another new character, an old lady, on 2 June,[6] a promotional picture showing Farnsworth watch Leela and Amy kissing Fry on 3 June,[7] a design of a nose-pronged device on 4 June,[8] a video clip featuring Kif, Amy, Leela, Fry and Bender in what resembles the inside of a tree - where Leela and Amy kiss-fight over Fry - on 5 June[9] and the fifth Futuramapodcast[10] - which revealed more information about Butterfly Derby, Tank (including the fact that she is actually named "Truck"), Nectar, the old lady, the plot and the nose-pronged device - on 6 June. On 28 June, MSN TV revealed the episode's air date.[11]

In an interview with David X. Cohen on wired.com, it was revealed that the Butterfly Derby sport is played on the low-gravity surface of the Moon, where players can strap on wings and attack their opponents. Cohen added: "It's like a roller derby, with human butterflies."[12]

On 12 July, following the broadcast of the episode "Zapp Dingbat", the public were given the opportunity to participate in a live chat with the Futurama cast and crew. Several clips of "The Butterjunk Effect" were shown during the live stream.[13]

While delivering the moonrocks when the gang is playing with them in the moon's reduced gravity, Amy says that they're so light that she doesn't need her "over-the-shoulder boulder holder". This is an older, silly rhyme referring to a bra.

Trivia

In this episode, the Grand Midwife introduces herself as the Grand Butterfly Curator, revealing the last of her five grand jobs.

Goofs

In one scene, Bender is seen smoking a carrot, but when the camera changes angles, the carrot is gone.

The Professor mentions the moon rocks being taken to Earth by the Apollo program, although knowledge about the first moon landing has been lost in the 31st century. Or maybe, after Fry and Leela found the landing site, Apollo became publicly known again, which would also explain why the Moon claimed the rocks then and not earlier.

During the final fight, Leela says she once killed a sea turtle with the boots she is wearing, but the boots are not the ones she usually wears. They are the same as Amy's.

The fact they are not her normal boots doesn't mean she did not kill a sea turtle in them.